Lack of power in VTOL mode!

Hi there…
Did a anyone had problems with lack of power in VTOL mode? Is there any parameter that can directly affect effectiveness of my command?

Already checked ESC (calibration, timing). changed to new Lipo, changed PDB to direct cables. Is there anything that could cause such effect in MissionPlanner? At full throttle it is barely getting to altitude in VTOL mode in FBWA it is barely holding it altitude.

Those problems arise some time ago and it is getting worse and worse. It had some major crashes… yep that is true.

Can anyone give me some advise or suggestion? Loosing my mind over it :frowning:

Log link:

One thing that came up to our minds is that those motors are rated for 26A and we are pushing them waaaay pass that point, and that probably is the issue - degrading motors cause by to much current :frowning: poorly chosen for VTOL

Can someone point me in right direction for good motor for vectored thrust? 2 motors, MTOW ~8kg, 6s or 8s.

Happy flying :slight_smile:

You’ll need to provide more details of your build.

  • Make and model of aircraft, motors, ESC and props.
  • Firmware version.
  • Maybe a video?

Good luck.

Hi there :slight_smile:

Here is a link for our wing:

Model: flying wing tilted motor belly sitter
ESC: we are currently using Skywalker 80a and Master Spin 75a opto
Props: APC 15x10
Firmware: 4.1.7 and 4.2.2

Leveled flight there is no problems but when it comes to vtol… well lack of power and the motors are to power-hungry. Wing on its own with battery weights around 4.5kg plus payload around 1.5kg that is our target (more is even better :wink: :slight_smile:

Thanks in advance :slight_smile:

What’s the motors’ make and model?
Can’t watch or open the video.

Current motor are TMotor 4014 400kv on 6s:

Link on GoogleDrive for the clip:

Perhaps it’s simply underpowered/overweight? What’s the average commanded motor outputs at Hover?

As @dkemxr mentions, it’s underpowered. A quick plug into eCalc at 4.5kg, you only have a 1.4 Thrust to weight ratio.

With your planned 1.5kg payload, you’re only at 1.0 T/W ratio.

If this was a quadplane design, you’re desired 8kg MTOW would be achievable.

Good luck.

As I said:) I’m noob to all of this so sorry for all those dump question.

Have to redesign it after someone else… tough task to do.

Didn’t know about eCalc until now… Great stuff thank you for the tip :slight_smile: @rollys

Some things are going to be calculated then :slight_smile:

HI there @dkemxr

Well at the begging was around 50-60%. But motors start to degrade fast now… well is at full throttle is barely rising in VTOL, unflyable.

That is why we art to look fro issues with the setup.

To much current and temp for those motors killed them.

I started to look for some better motors for our needs. But not sure what to choose, already have bunch of them lying around useless.

Since we have a lot of 15x10 props trying to find something up to that config with 6s 10000mah.
Can anyone of you guys can point me out i right direction :wink:


Decided to go with SunnySky X4125-440-III and Scorpion SII-4025-440.

Hope that this will be finally the one :wink:


Can anyone explain me secret behind flight time in eCalc, Because no mater what I will choose it always shows like 10 min max, but still with similar result I could get like 90 min flight time easily :slight_smile:

Can you provide the approximate wing area? Also, what’s the distance between the motors? Will try to get you a more comprehensive calculation.

Sorry for the delay.

Wing area is approximate 1600. Motor distance 1100 mm.

Thanks in advance :slight_smile:

1600mm seem to be the wingspan. What is average wing chord so we can calculate the wing area?


Wing span is 2600mm. Wing chord at tip is 240mm and root chord is 400mm. But You will have to add some more area to cover up bulge in the middle based on provided photo:

Wing profile is Eppler 374 and main body is FAUVEL 14%.

Thanks for you help :slight_smile:

Here are the raw numbers plugged into eCalc. Take a look at the values entered and take it for what it’s worth. It’s far from what you can potentially get but it gives an idea if the your design is workable. As I’ve mentioned in a previous post, personally, I would’ve done this as a 4+1 Quadplane to maximize payload capability and endurance in FW flight.

Good luck.

FAUVEL FW Belly Sitter.pdf (837.1 KB)
FAUVEL MC Belly Sitter.pdf (878.5 KB)

Thanks for great help. That the news I was looking for :slight_smile: